1. Field of the Invention
The present invention relates to an oral composition comprising 2xe2x80x2-hydroxypropiophenone.
2. The Related Art
One of the commonest flavours used in oral care formulations is mint. Further, there are many different flavour ingredients which effect several different minty flavours to the consumer, for example, peppermint oil, spearmint oil and wintergreen oil to name a few. Wintergreen oil is a particularly popular flavour material and is commonly used in oral care formulations, particularly toothpastes, all over the world.
The flavour molecules which are usually used to impart a wintergreen flavour to such oral compositions are only ever used in toothpastes which have a substantially neutral pH, for example, the paste marketed by the applicant under the brand name xe2x80x98Close-up(copyright)xe2x80x99.
It is well known in toothpaste manufacture that the main ingredient in wintergreen flavour, methyl salicylate, is unstable in alkaline pH ranges.
This presents a problem since some of the more popular oral care compositions are at a substantially alkaline pH. For example, bicarbonate toothpastes are marketed by many of the oral care consumer products suppliers and are only ever made at substantially alkaline pH ranges. Further, where calcium carbonate is used as a polishing agent, for example, in the developing and emerging markets, the general pH of a formulation is also substantially alkaline, often as high as 10.
The prior art literature also refers to wintergreen oil as a flavour ingredient. WO 98/31242 (Wrigley) discloses the use of 2xe2x80x2-hydroxypropiophenone as a substitute for the major wintergreen ingredient methyl salicylate. However, no mention is made of the fact that 2xe2x80x2-hydroxypropiophenone can also be used to overcome the disadvantages of methyl salicylate as a wintergreen flavour ingredient where the pH is alkaline.
It is an object of the invention to provide an oral composition which is stable, has a wintergreen flavour and is at an alkaline pH.
Accordingly, the present invention provides an oral composition including a wintergreen flavour imparting ingredient and having an alkaline pH, wherein the wintergreen flavour imparting ingredient is 2xe2x80x2-hydroxypropiophenone.
2xe2x80x2-hydroxypropiophenone is commercially available from Sigma-Aldrich Company Ltd., The Old Brickyard, Gillingham, Dorset SP12 4XT, United Kingdom. A synthesis for the compound may be found in Org. Synth. 13, 90 (1933).
It is an essential feature of the invention that the pH of the composition is alkaline. By this is meant that it is not neutral, or substantially neutral, and ranges from about 7.5 to about 12.
In a particular embodiment the pH is greater than 7.5 and preferably above 8.5.
The oral composition according to the invention typically comprises from 0.0001 to 1% by weight 2xe2x80x2-hydroxypropiophenone, preferably from 0.001 to 0.75% and especially from 0.1 to 0.2% by weight.
In a further aspect, the invention relates to a method for imparting a wintergreen flavour to an oral composition of alkaline pH by incorporation into the composition 2xe2x80x2-hydroxypropiophenone.